Oil-Cooled Carbon Seal Seat with Centrifugal Face Cooling
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Solution Overview
Problem
Carbon seals in gas turbine engines face challenges in efficiently dissipating frictional heating due to sliding engagement, with existing oil-cooled systems either having limited cooling effectiveness or risking heat generation and wear from uneven thermal expansion.
Innovation Solution
A seal system with a rotating second member featuring a circumferential array of apertures and a plenum, along with spiral or threaded passageways, that centrifugally drives oil flow to cool the seat face, maintaining the cooling fluid separate from the interface and enhancing heat transfer through surface enhancements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If oil is delivered through passageways to cool the seat face, then cooling effectiveness is improved, but the oil may contact the sealing interface causing lubrication and heat generation
Solution Approach 1:
The patent extracts the harmful function of oil contact with the sealing interface by providing a separate cooling fluid delivery system. The cooling fluid is delivered through dedicated passageways that terminate at the seat face, allowing cooling without oil contamination of the sealing interface between the carbon seal and metal seat.
Solution Approach 2:
The patent segments the fluid delivery system into separate pathways: one for cooling fluid delivery to the seat face and another for the sealing interface. This segmentation prevents the cooling fluid from interfering with the sealing function while maintaining effective cooling of the seat face.
2Temperature
If cooling fluid is delivered directly to the interface, then cooling is effective, but uneven thermal expansion and wear occur
Solution Approach 1:
The patent removes the cooling fluid delivery location from the sealing interface itself, instead delivering cooling fluid to the seat face adjacent to or behind the sealing interface. This extraction prevents the cooling fluid from disrupting the sealing contact while still achieving effective heat removal from the seat face.
3Temperature
If spiral or threaded passageways are used, then heat transfer is enhanced, but device complexity increases
Solution Approach 1:
The patent employs spiral or threaded (curved) passageways instead of straight channels to deliver cooling fluid to the seat face. These curved geometries enhance heat transfer efficiency by increasing fluid residence time and promoting turbulent flow patterns, while the spirals are integrated into the seat structure in a space-efficient manner.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution provides more uniform cooling, reducing heat generation and wear, while maintaining effective sealing by ensuring the cooling fluid remains attached to the seat face, thus enhancing the operational efficiency and longevity of the carbon seals.
Implementation Method 1
A flowpath from the collection channel passes radially outward axially spaced from the seat face to cool the seat face
Implementation Method 2
The sliding engagement causes frictional heating
Data Source
AI summary
A seal system has: a first member; a seal carried by the first member and having a seal face; and a second member rotatable relative to the first member about an axis. The second member has: a seat on a first piece of the second member, the seat having a seat face in sliding sealing engagement with the seal face; and a radially outwardly closed collection channel for collecting centrifuged oil; a second piece encircling and attached to the first piece and having a circumferential array of apertures; and cooperating with the first piece to define a plenum; and a flowpath from the collection channel passing radially outward axially spaced from the seat face to cool the seat face and passing axially away from the seat face in the plenum.